Scientific and commercial potential of nanoparticle materials currently attracts much attention. This fact is true in the case of nanoparticle titanium dioxide. Methods of making nanoparticle titanium dioxide include colloidal precipitation, mechanical grinding and gas phase nucleation and growth.
Gas phase synthesis offers advantages over both colloidal precipitation and mechanical processes, but in gas phase synthesis (sometimes called an aerosol process) continues to face challenges in control of particle size distribution and degree of aggregation and agglomeration.
Various methods have been taught to control nano particle primary particle size and particle size distribution. For example, U.S. Pat. Nos. 5,935,293 and 5,749,937 to Detering et al., U.S. Pat. Nos. 5,788,738 and 5,851,507 to Pirzada et al., and U.S. Pat. No. 5,935,293 to Rao et al., all teaching methods related to rapid quench or expansion of product gases.
Applicant's own U.S. application Ser. No. 60/434,158 teaches a flow homogenizing device that provides a nearly 1-dimensional flow and concentration profile in the reaction zone as a means to narrow particle size distribution.
U.S. Patent Application Publication 2002/0004029 A1 to Jang et al. teaches a flame hydrolysis in which hydrogen is one of five reactants fed into a reactor to produce titanium dioxide from reaction of titanium tetrachloride. Russian Patent SU (11) 1043154 teaches a flame hydrolysis of titanium tetrachloride in an oxygen-containing gas and hydrogen, and Japanese Kokai Patent Application Hei 5[1993]-84948 teaches a vapor phase hydrolysis reaction of titanium tetrachloride. Each of these publications teach a method to make titanium dioxide from titanium tetrachloride that involves the presence of hydrogen, but in each case a hydrogen oxygen reaction is the source of the flame.